It is known in the art that optical detectors generally are one of two types. A first type utilizes carrier pair generation (electrons and holes) in semiconductor materials to modify the associated material conductivity. A second type utilizes photoelectrons, liberated through absorption of photon energy by electrons residing at or near the surface of conductive materials.
In the instance of the first, it has been observed experimentally that modification of the conductivity of the material is directly related to the intensity of incident optical energy in addition to the wavelength of the incident energy.
In the instance of the second it is observed that the magnitude of photoelectron emission is directly related to the intensity of incident optical energy; but, above a determinate threshold level, the magnitude is relatively insensitive to the wavelength of the incident optical energy.
For many anticipated applications the operating features of the existing art, as described previously, are undesirable. Accordingly, there exists a need for an optical signal detector which overcomes at least some of these shortcomings.